Policy pressures in the USA to transition parents from public assistance to work and concerns about the effects of early maternal employment on children highlight the importance of studying predictors of the timing of postpartum maternal employment. Little attention has been given to postpartum employment patterns of low-income ethnic minorities and immigrants, whose working conditions and employment prospects are different from white, middle-class mothers. Using a sample of low-income Mexicans, Dominicans, and African-Americans (N = 310), we studied whether and when mothers start working the first year following childbirth, and what factors promote or delay postpartum employment. Using discrete-time survival analysis, we modeled the odds of working at each month and tested the influence of family context, mothers' work and family values and plans, maternity leave benefit, and instrumental support availability on the timing of employment. By 11 months, half of the mothers had started working. Having maternity leave, plans to work, childcare arrangements, and a strong work orientation increased the odds of working. Household earnings were related to postpartum employment, but this effect varied over time. For African-Americans, instrumental support availability predicted earlier returns to employment, whereas for Mexicans and Dominicans it related to later returns to employment.